Maybe, but everything they are talking about doing, aside from their monster and DM book, are modules and campaign settings. So as long as that remains the case I will be in total control of what is available to my players.
Besides, it is the story that keeps players coming back. C&C definitely will allow me to focus on story. After the Castle Keeper book comes out I'll decide what I'll convert from other systems. I definitely want to keep some kind of good skill system.
Another thing we do have to remember, and previous posters to this thread have commented about it, is a DM and their players do have to be on the same page about what they expect to get out of a game. Now if you have a DM who cares more about playing a character with personality and a player or players who are looking for the most powerful PrC and feat combo's, you have a major problem.
So if you want to be a powergamer/tweaker, have a DM who likes doing the same thing. If you want to have engaging story plots that make you want to do something in the game for reasons other than the treasure, find a good story telling DM and have players who like the story more than the next cool feat, or power/ability gained from the next level of their PrC.
So systems defintiely have a big impact on how a game goes. Otherwise I wouldn't prefer Classic Traveller over D20 or GURPS Traveller, or Shadowrun over Cyberpunk. If systems didn't have an impact no one would have cared that 3E D&D came out, they would have stayed with 2E. Of course some have, just like some stayed with 1E and Old D&D. So systems having an impact on a game are a no brainer. Just like the quality of the DM and the players also effects a gaming experience are a no brainer.